Standard transmission and recording of high resolution television

Abstract

The full potential of high resolution television by synchronized modulation of the scan lines at the camera and display unit is achieved in standard transmission through band limited channels by: separating out of the video signal from the television camera the modulation frequency as sidebands with pixel information, for example 7.16±1/2 MHz in the case of a color subcarrier at 3.58 MHz under the NTSC standards and pixel information modulated on sidebands in a narrow band (about ±1/2 MHz); converting the sidebands with pixel information down to within the color subcarrier band (in the range of 3.75 MHz to 4.2 MHz) using a heterodyne converter; and adding back to the video signal out of the camera the down-converted sidebands with pixel information before processing it through the color encoder for transmission through the bandwidth limited channel. The transmitted signal may be received and displayed by a standard television receiver or monitor, but to achieve the higher resolution which modulation of the scan line affords, the receiver, or monitor, must be modified to convert the color reference frequency to the line scan modulation frequency (synchronized with the color subcarrier) and, while using the color reference at the standard frequency for color decoding, using the modulation frequency to modulate the line scan of the color display tube at the same time the detected video signal is filtered to separate the down-converted sidebands with pixel information, convert the sidebands with pixel information back up to the modulation frequency using a heterodyne converter, and add the up-converted sidebands with pixel information back into the detected video signal for processing in the receiver or monitor modified to modulate the scan lines for display.

What is claimed is: 
     
       1. In a television system having a bandwidth limited transmission channel comprised of a camera and a display unit, a method for improving vertical resolution of a video signal produced by said camera, frame by frame, comprising the steps of modulating the vertical beam deflection of said camera while producing said video signal for each line of a frame, said modulation having a frequency higher than the upper bandwidth limit of said transmission channel for causing each line scanned to undulate about the normal straight line scan, separating out of the video signal from said camera vertical modulated sidebands with pixel information which is narrow band; converting said sidebands with pixel information down to a frequency within said bandwidth limited channel using a converter; adding back to the video signal out of the camera the down-converted sidebands with pixel information before processing it further for transmission through the bandwidth limited channel; modulating the vertical beam deflection of said display unit with the same phase and relative amplitude as the modulation of the vertical beam deflection of said camera for display of each line of a frame in the same pattern as scanned by said camera, and at the display unit detecting the video signal transmitted; separating the down-converted sidebands with pixel information from the detected video signal, converting the separated sidebands with pixel information back up to said modulation frequency used at said camera; and adding the up-converted sidebands with pixel information back into the detected video signal before processing it further for display. 
     
     
       2. A method defined by claim 1 wherein said video signal is transmitted to a display unit together with information for synchronizing the modulation of the vertical beam deflection in said display unit with the same effect of modulation of the vertical beam deflection in said camera on said video signal. 
     
     
       3. A method as defined by claim 2 wherein modulation at said camera is at a fixed frequency controlled by a stable oscillator, and modulation at said display unit is at said fixed frequency controlled by a stable oscillator, and wherein said information for synchronizing the modulation of said display unit is comprised of bursts of cycles from said stable oscillator at said camera gated to said display unit during line blanking periods of said video signal, and said display unit accepts said bursts for synchronizing the phase of said stable oscillator at said display unit. 
     
     
       4. A method as defined by claim 3 wherein said television system utilizes a color television camera, and said oscillator at said camera generates a carrier for color modulation, and said stable oscillator at said display unit generates a color reference for use in color decoding. 
     
     
       5. A method as defined in claim 4 wherein said color carrier is at 3,579,545 Hz and each frame includes 525 lines at a rate of 15,734 lines per second, including the step of deriving from said color carrier a signal at some even multiple for modulation of each line at both said camera and said display unit. 
     
     
       6. In a television system having a bandwidth limited transmission channel comprised of a camera for producing a video signal and a unit for display of said video signal, said camera having a means for vertical and horizontal deflection of an electron beam driven for scanning a predetermined number of horizontal lines for each video frame, and said display unit having means for vertical and horizontal deflection of an electron beam synchronized for displaying said frame, said camera having means for modulating the vertical beam deflection at a rate to produce cycles of undulation about the normal straight line scan thereby producing sidebands with pixel information at a frequency higher than the upper bandwidth limit of said transmission channel, and said display unit having means for modulating the vertical beam deflection of said display unit with the same phase and relative amplitude as the modulation of said video signal for display of each line of said frame in the same pattern as scanned by said camera, thereby displaying the sideband information, said television system further including means for separating out of the video signal from said camera said sidebands with pixel information within a narrow band; means for converting said sideband information with pixel information down to a frequency within said bandwidth limited channel using a heterodyne converter; means for adding back to the video signal out of the camera the down-converted sidebands with pixel information before processing it further for transmission through the bandwidth limited channel; and at said display unit means for detecting the video signal transmitted; means for separating the down-converted sidebands with pixel information from the detected video signal, means for converting the separated sidebands with pixel information back up to the modulation frequency used at said camera; and means for adding the up-converted sidebands with pixel information back into the detected video signal before processing it further for display. 
     
     
       7. Apparatus as defined in claim 6 wherein said deflection means for said camera is comprised of a stable frequency oscillator operating at a predetermined frequency driving vertical deflection means associated with said camera, and said deflection means for said display unit is comprised of a stable oscillator operating at said predetermined frequency driving vertical deflection means associated with said display unit, and including means for synchronizing the phase of said oscillator for said display unit with information transmitted by said camera with said video signal. 
     
     
       8. Apparatus as defined in claim 7 wherein said oscillator for said camera is comprised of an oscillator for color modulation, said oscillator for said display unit is comprised of an oscillator for color demodulation, and said information transmitted by said camera with said video signal is comprised of bursts of cycles of said camera oscillator gated during line blanking periods of each frame. 
     
     
       9. Apparatus as defined in claim 8 wherein each frame includes 525 lines scanned at a line rate of 15,734 lines per second, wherein said deflection means for said camera includes a frequency doubler and said oscillator for said camera operates at 3.579545 MHz, and wherein said deflection means for said display unit includes a frequency doubler, whereby each scan line in both said camera and said display unit includes 455 modulation cycles. 
     
     
       10. In a television system for transmitting from a color camera to a receiver through a bandwidth limited channel, said camera having three camera tubes, each with a separate one of red, green and blue filters, a method for improving vertical resolution of a video signal produced by said camera frame by frame comprising the steps of effectively modulating the vertical component of said green filtered camera tube while producing said video signal for each line of a frame, said modulation causing each line scanned by said green tube to undulate about the normal straight line scan at a frequency higher than the upper limit of said channel with an amplitude sufficient for each cycle of undulation to intrude the scan area of adjacent lines in a frame, separating out of the video signal from said camera vertical modulated sidebands with pixel information within a narrow band; converting said sidebands with pixel information down to a frequency within said bandwidth limited channel using a heterodyne converter; adding back to the video signal out of the camera the down-converted sidebands with pixel information before processing it further for transmission through the bandwidth limited channel, and modulating the vertical beam deflection of said receiver with the same phase and relative amplitude as the modulation of said green filtered video signal for display of each line of a frame in the same pattern as produced by said color camera, and at the display unit detecting the video signal transmitted; separating the down-converted sidebands with pixel information from the detected video signal, converting the separated sidebands with pixel information back up to said modulation frequency used at said camera; and adding the up-converted sidebands with pixel information back into the detected video signal before processing it further for display.